Method and apparatus for detecting malfunctioning print elements in postage meter indicia printer

Abstract

In a mailing machine, an image element included in a postage meter indicium printed on a mail piece is transported past a linear image capture device. The image capture device is operated to produce a smeared image of the image element. The smeared image is then automatically analyzed to detect failures in the print elements of a postage meter that is part of the mailing machine.

1. A method comprising:
 transporting a mail piece along a transport path past a print head and an image capture device, the print head including a linear array of print elements, the array oriented transversely to a direction in which the mail piece is transported, the image capture device downstream from said print head along said transport path, the image capture device including a linear array of image capture elements, the array of image capture elements oriented parallel to the array of print elements, the image capture device positioned to capture an image of an indicium printed by the print head on the mail piece; 
 while the mail piece is being transported past the print head, selectively operating ones of the print elements to print an image element on the mail piece; 
 detecting a leading edge of the mail piece; and 
 triggering the placing of the image capture elements in an image capture mode at a predetermined time interval after a point in time when the leading edge of the mail piece was detected so that the image capture elements are in the image capture mode before the image element reaches the image capture device; 
 while the mail piece is being transported past the image capture device maintaining the image capture elements in the image capture mode; 
 maintaining the image capture elements in the image capture mode until the image element has entirely passed the image capture device; 
 ending the image capture mode after the image element has entirely passed the image capture device; and 
 analyzing image signals generated by said image capture elements during said image capture mode to determine whether any of said print elements has failed. 
 
     
     
       2. The method according to  claim 1 , wherein the image element is a two-dimensional barcode that is part of the indicium. 
     
     
       3. The method according to  claim 1 , wherein the image element is a logo that is part of the indicium. 
     
     
       4. The method according to  claim 1 , wherein the image element is a POSTNET barcode. 
     
     
       5. The method according to  claim 1 , wherein the print head is part of a postage meter. 
     
     
       6. The method according to  claim 5 , wherein the transporting is performed by a mail piece transport mechanism that is part of a mailing machine in which the postage meter is installed. 
     
     
       7. The method according to  claim 1 , wherein said image signals represent an image of said image element, said image of said image element being a linear image that is one pixel wide. 
     
     
       8. The method according to  claim 7 , wherein said analyzing begins at a predetermined distance from a top end of the image of said image element and ends at a predetermined distance from a bottom end of the image of said image element. 
     
     
       9. The method according to  claim 7 , wherein said analyzing includes detecting beginning and ending points of said image of said image element. 
     
     
       10. The method according to  claim 7 , wherein said analyzing step includes detecting gaps in said image of said image element. 
     
     
       11. The method according to  claim 1 , wherein said transporting is performed at a rate of at least about 50 inches per second. 
     
     
       12. The method according to  claim 1 , wherein the print elements are ink jet print elements. 
     
     
       13. A mailing machine comprising:
 a transport mechanism for transporting a mail piece along a transport path; 
 a print head located adjacent the transport path for printing a postage meter indicium on the mail piece while the mail piece is transported past the print head, the print head including a linear array of print elements, the array oriented transversely to a direction in which the mail piece is transported; 
 an image capture device located adjacent the transport path downstream from the print head, the image capture device including a linear array of image capture elements, the array of image capture elements oriented parallel to the array of ink jet print elements, the image capture device positioned to capture an image of the postage meter indicium printed by the print head on the mail piece; and 
 at least one control device coupled to the transport mechanism, the print head and the image capture device, the at least one control device operative to:
 control the print head so as to selectively operate ones of the print elements to print an image element on the mail piece as part of the postage indicium; 
 control the image capture device (a) such that the image capture elements are (i) placed in an image capture mode before the image element reaches the image capture device, and (ii) maintained in the image capture mode until the image element has entirely passed the image capture device, and (b) such that said image capture mode is ended after the image element has entirely passed the image capture device; and 
 analyze image signals generated by said image capture elements during said image capture mode to determine whether any of said print elements has failed and 
 a sensor located adjacent the transport path between the print head and the image capture device, the sensor for detecting a leading edge of the mail piece, the sensor coupled to the at least one control device, the at least one control device responsive to the sensor by triggering the placing of the image capture elements in the image capture mode at a predetermined time interval after a point in time when the sensor detected the leading edge of the mail piece. 
 
 
     
     
       14. The mailing machine according to  claim 13 , wherein said image signals represent an image of said image element, said image of said image element being a linear image that is one pixel wide. 
     
     
       15. The mailing machine according to  claim 14 , wherein the image element is a two-dimensional barcode included in the postage meter indicium. 
     
     
       16. The mailing machine according to  claim 15 , wherein said analyzing function includes detecting gaps in said image of said image element. 
     
     
       17. The mailing machine according to  claim 13 , wherein said transporting is performed at a rate of at least about 50 inches per second. 
     
     
       18. The mailing machine according to  claim 13 , wherein the print elements are ink jet print elements.